For simulation in computer aided surgical interventions the detection of impingement between parts of the patient's anatomy and/or implants is often of key importance. Impingement (collision) detection methods used in the existing literature seem to be unsuitable for two reasons. First, a polyhedral approximation of an anatomical model is not appropriate, since medical images are quite irregular and are essentially non-linear. Secondly, geometric and temporal coherences are not always available, since just final results may be of interest.
A method for performing surgery on a body portion with the steps of loading previously established surgical plan data into a computer, registering a three-dimensional computer model of the body portion stored in the surgical plan data to the body portion of the patient, providing at least one surgical tool, positioning the surgical tool relative to the body portion and performing the surgery is known from U.S. Pat. No. 5,682,886 to Delp. Before the surgical procedure may be effected image data of the body portion must be gathered by means of applying a radiant energy means e.g. magnetic resonance imaging, X-ray devices or computed tomography imaging devices. The so gathered image data is then stored in a memory means for storing image data and the stored image data read into a computer interfaced to the memory means, whereby the computer has a visual display means for displaying images generated in at least one process step.
The surgery plan data comprises the three-dimensional computer model of the body portion and data relating to at least one prosthesis of defined size and position relative to the body. Before performing the surgery the three-dimensional computer model of the body portion is registered on-site to the actual body-portion by means of suitable magnetic devices, acoustic devices or optical devices such as a wand with LED's that are sensed by external cameras.
Furthermore, this known surgical procedure subsystem allows the surgeon to implement the preoperative plan by accurately guiding the placement of the prosthesis on the patient's bone. Thereby, the position measurement device reports to the computer the three-dimensional position of a movable probe, surgical instrument or component of a prosthesis. In case a MR imaging machine (Magnetic Resonance) is used data points are automatically collected in order to register the body portion and the instruments to the three-dimensional computer model. The use of such a MR imaging machine provides the surgeon a real-time image of the body portion and the instruments. Instead of a MR imaging machine a intraoperative CT device (computer tomography) could be used.
This method has the disadvantage that the impingement of two bodies e.g. the body portion and a surgical instrument may only be detected in real-time by using an imaging device, e.g. a MR imaging machine intraoperatively.